About this release

This annual release from Public Health Scotland (PHS) provides statistics on high, low and healthy body mass index (BMI) for Primary 1 school children (those aged around 5 years old), and includes data for school years 2001/02 to 2021/22. Statistics in this release are derived from height and weight measurements collected at health reviews in Primary 1.

Main points

  • In school year 2021/22, 74.7% of Primary 1 children measured had a healthy weight, 24.1% were at risk of overweight or obesity and 1.1% were at risk of underweight.
  • The percentage of children at risk of obesity in 2021/22 (11.7%) was lower than in 2020/21 (15.5%), but remains higher than that in 2019/20 (10.4%).
  • Marked socioeconomic inequalities in child healthy weight persist, particularly in the percentage of children at risk of obesity. In 2021/22 15.5% of children living in the most deprived areas were in this category, compared with 7.3% of those living in the least deprived areas.
Image caption Percentage of Primary 1 children at risk of obesity by deprivation, school years 2001/02 to 2021/22, Scotland
  • Boys in Primary 1 remain slightly less likely than girls to have a healthy weight.


In school year 2021/22 a total of 52,732 children had valid height and weight measurements recorded in Primary 1. This is approximately 92% of all children in Primary 1. Coverage was significantly higher in 2021/22 than in the previous two years, when it was low due to the impact of the COVID-19 pandemic on school opening and conduct of health reviews.

A child’s BMI is calculated by dividing their weight (in kilograms) by their height (in metres) squared. Children are then allocated to a healthy or unhealthy weight category by comparing their BMI to the range of BMIs seen among a reference group of children of the same age and sex. This summary provides information on the proportion of children found to be at risk of having an unhealthy weight based on the thresholds used for monitoring the health of the child population ('epidemiological thresholds'). The full report also provides information on the proportion of children found to have an unhealthy weight based on the narrower clinical thresholds used by health professionals caring for individual children. Monitoring healthy weight across the child population is a way of seeing how well the needs of children are being met. Maintaining a healthy weight through childhood is associated with many health benefits.

Further information

The next release of this publication will be December 2023.

General enquiries

If you have an enquiry relating to this publication, please email phs.childhealthstats@phs.scot.

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Older versions of this publication

Versions of this publication released before 16 March 2020 may be found on the Data and Intelligence, Health Protection Scotland or Improving Health websites.

Last updated: 21 March 2024
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